Three-chamber clearance unloader



4 1616991 1927' I s. B. REDFIELD THREE-CHAMBER CLEARANCE UNLOADER Filed Aug. 4, 1926 4 Sheets-Sheet l 191 v H18 ATTRNEY.

Feb. 8 1927.

, 1,616,991 s. B. REDFIELD.

THREE-CHAMBER CLEARANCE UNLOADER Filed Aug. 4, 1926 4 Sheets-Sheet 2 1 IN V EN TOR.

.22 X02123 geayk'elaf H/S A ORNEY Feb. 8, 1927.

1,616,991 8. B. REDFIELD THREE-CHAMBER CLEARANCE UNLOADER Filed Aug. 4, 1926 Sheets-Sheet 3 U D E INVENTOR. Sgzozz/dejz B-RG 1! Feb. 8 1927.

s. B. REDFIELD THREE-CHAMBER CLEARANCE UNLOADER Filed'Aug. 4, 1926 4 Sheets-Sheet 4 11 j w 3 DI V H/s AT ORNEY Q J r loading, a

Paten ted Feb a8, i927. I

.UNITE'D .sTA.

TES fix-T NT or 1,616,991] FICE.

SNOWDEN B} REDFIELD, OF EAS'ION, SYLVANIA, ASSIGNOR TO ILl'GERSOLLERAND COMPANY; OF JERSEY CITY, NEW JERSEY, A CQRRORATION OF NEW J'EB1SE.

THREE-CHAMBER CLEARANCE UNLOADER.

Application filed August 4,

a compressor to be unloaded or loaded in successive stepsbymeanspf aplurality' of. clearance chambers and clearance valves and'an inlet valve. opener, thus reducing the number of clearance chambers required for a given number of'steps. I

15 Another object of the invention is to enable the compressor to be unloaded by means of clearance chambers, so arranged that there are more chambers atone end of'the cylinder than fat the other,end, and to-accomplish' this'purpose' an inlet valveopener is provided for one of the inlet valves at the end of the cylinder, having the lesser number of clearance chambers.v By proper:

. lv .manipulating the clearance valves and 25 the inlet valve opener, the desired number. of steps may be effected and tbennloading' system iscapable of different modes of op- Y eration for accomplishing the same results, because the clearance valves and the inlet valve -opener-angry be manipulated in dif'-.

ferent sequences depending-on the particu-% lar compressor.

In the preferable form of the invention,

' two clearance chambers and clearance valves are'provided for one end ofthe-cylinder and.

- one clearance chamber and: clearance valve and an inlet valve opener for one of the inlet valves are provided for the opposite end of the cylinder. This is a Simple form of the; invention and with such construction different modified forms of ,automatcregulator may-be conveniently used for varying the sequences of operations ,in producingsteps of unloading andloading.

The invention is illustrated in some'of its 7 preferred forms in the accompanying drawings,in which-P p Figure 1 is adiagrammatic illustration partly in vertical longitudinal section, showing one form of the inventio 1 Y a "Figure 2 illustrates the-indigato'r cards for .the compressor cylinder 'for eachistep ofun Iigne 3 a diagrammatic view of a mo cat1on,.

pipe 1, since .closed', and again reopened inlast to open.

'In carrying out 1926. Serial No. zaoes.

Figure 4 shows the indicator cards for Figure 3, J

Figure '5 is a diagrammatic view of a.

modification, v v

Figurefi shows the indicatorcards for 00 Figure Tis a diagrammatic view of another modification, and v Figure '8. shows the .indicator cards for Figure7. Referring to the drawings, the cylinder A of a'compressor is provided with the'piston L B and air drawn in at the intake C is discharged at the discharge outlet 1) to-the receiver E. The cylinder is provided with .an unequal numberyof clearance chambers at ealh end, and in vtlns in stance, one clearance chamber F is shown at one end, as for instance, the crank end and two clearance chambers G" and H are shown at the'head en v The cylinder isprovided with the usual inlet and discharge valvesJ and K which may be of any suitable type, as-for instance, plate valves, and one inlet valve L at the crank end of the cylinder is provided with a suitable valve opener.- .For this purpose the valve stem may be formed with a piston 0 operating in the cylinder P, and fingers Q, are adapted to push the valve L open when pressure fluid is supplied through the pipe 4 behind the piston A spring'R T retracts the fingers normally.

The clearance chambers are provided with the clearance valves S and each :clearance valve has a pistonT operating in the cylin? der'U, Springs V normally maintain the clearance" valves .closed and pressure flilid is led tuft-he cylinders for opening the valves by means of the pipes 1, '2 and 3. '-In the case of the cylinder for the clearance valve of the chamberF, the ventW is of s'ufli-* cient size to permitthe valve to quickly close in case pressure is cut-oil from the the clearance valvc for this chamber F. is'f adapted to .be'fopxened, then t e cycle of operations. The other, two clearance u valves S for the chambers Gand' H' remain opena fter "they are once opened throughout the 9 complete cycle, and the inlet valve L is the.

the steps oiiunloading, the v clearance chamber F is rst openedj'q. Pryor duce threequarters load.- Then chamber F is closed and chambers G and H are both opened to produce half load. These two chambers G and H then remain open and the .chamber F is reopened to produce one quarter load. Finally the inlet valve L is opened while the two clearance chambers Gr and H remain open for no load, and this cycle is repeated in reverse order for re loading the compressor.

The indicator cards for both ends of the cylinder are indicated diagrammatically in Figure 2, from which it will be seen that in step I, the head end of the cylinder is fully'loaded and the crank end is one half unloaded by opening the clearance chamber F. In step II, the crank endis reloaded by the closing of the clearance chamber F and the head end of the cylinder is completely unloaded to produce half load on the compressor. In step III, the head end remains unloaded and the crank end is again half unleaded by the opening of the clearance pocket F, which produces three quarters load on the compressor. Finally, in step IV, the crank end is completely unloaded by the opening of the inlet valve L,- thus wholly unloading the compressor.

Any suitable automatic regulator, preferably responsive'to receiver-pressure, may be provided for carrying out these steps or any variations of these steps. A simple regulator is shown in Figure 1, comprising a cylinder at, having a piston 7) subjected to receiver pressure at one end through 'the pipe 0. The piston is guided on the feather or key cl to keep it from rotating, and an adjustable retracting spring 6 returns the piston to initial position. A vent f is preferably provided for the end of the cylinder opposite the pressure end. The pipe 1 leads to the'port g, the pipes 2 and 3 as shcwn are joined and lead to the port it, and the pipe 4 leads to the port The port it is in a different angular plane in the cylinder a from the plane of the ports (7 and h, and- ,the piston b is provided with the port 70 and groove 0 cooperating with the port h.

The piston is also provided with the ports 1), g and 1" and the passage 8 cooperating with the ports 9 and j..

In the operation of the regulator, let it be understood that the parts are all in the positions indicated in Figure 1 in which the compressor is fully loaded. As the pressure in the receiver increases, the first step of unloading will take place when the port 1? falls opposite the port'g, in which case, the clearance. valve S of the clearance chamber F will be opened to unload the compressor one quarter. At the next'step, the port 7.: in the piston b will register with the port kin the cylinder a, thus opening the clearance valves of both clearance chambers G and H at the oppositeend of the cylinder. Pressure will, however, be cut olf from the pipe 1 which will permit the clearance valve S of chamber F to close, so that the compressorwill'be half unloaded. In the next step, the port will register with the port 9 and reopen the clearance chamber F,-the two chambers G and H being maintained open which will produce one quarter load, and finally port 1) will register with port j to open the inlet valve L and completely unload the compressor. In the last step, the port 7' registers with the port 9 which maintains the clearance valve S of chamber F open, although this isuhnecessary as will be apparent. 1

For simplicity pfillustration and descrip-- tion, it will be assumed that the same regulator cylindera and piston 72 are used for the modifications of the invention, the only difference being the locations of the cooper- In all the modi cations, the first step of unloading is the" same for producing three quarters load, that is, the clearance chamber F is opened at the crank end of the cylinder to half unload that end of the cylinder.

. Referring to the modification shown in Figure 3 as stated, when the port 11 in the piston b registers with the port 9 in the cylinder a,pressure fluid is supplied through the pipe 1 to open the chamber F. In the next step, the port is registers with the port it which in this case is connected to the pipe 4 so that the inlet valve L is opened while at the same time pressure is cut off from port jg and pipe 1 so that'clearance valve S of chamber F-is closed and-the compressor operates at half load. Throughout the remaining steps the inlet valve L remains open, since the passage or groove o in the piston b continues to register with the port h. In step III, the port 12 registers with the port zf'whichis connected to pipe 2 in this case so that clearance chamber G is opened, thus producing. one quarter load,

finally, ports 0 and 1 register with the portsa and t, respectively, and since pipe 3 is connected with port u, clearance chamber H I will be opened while clearance chamber G remains open, and since inlet valve L is maintained openthe compressor iswholly unloaded.

The indicator cards in Figure 4 show the sequence of events because instep I, clearance chamber F at the crank end of the chamber is opened Instep II, this chamher is closed and the inlet valve L is opened to produce half load. In step III,the inlet 1 valve remains open and the clearance cham- 'ber G'is/opened at .the opposite end of. the cylinder to produce one quarterjload, and

- finally in step IV,- the inlet valve L remains open 41nd both chambers ,G

and H are open to p 'oduce no load.

The modification shown in: Figure 5, the pipel from clearance valve mechanism of chamber F is connected to port 9 as before.

ipe 4 from the inlet. valve opener of valve L is connected to the port it. Pi e 2'f1'om the clearance valve mechanism 0 chamber G 1s connected to the two'ports 'v and y, while the pipe .73 from clearance valve mechanism of chamber H is connected to tlfe two ports and m.

In the "first step of unloading, the port 17' as before registers with the port g which opens the clearance valve of chamber F for three quarters load. In the second step,-the ports p and g. respectively register with the ports '10 and 70 so that pressure fluid' is sup-' plied through both pipes -2 and 3 to open the clearance valves to chambers G and H at the head end of the cylinder while pressure fluid is cut off from the pipe 1, so that the clearance chamber F at. the crank end of the cylinder is closed, thus producing half load. 'In the third step, port In in the piston b registers-with the port It in the cylinder at so that pressure fluid is supplied through I pipe 4 from port It, to the-valve openerof the inlet valve L. thus "completely unloading the crank end of the cylinder, whilea't-the same time port p registers with port :0 which supplies pressure fluid through pipe 3 to keep open the clearance valve of chamber H at the head end of the cylinder and cut off the pipe 2 so that chamber G is closed and the compressor is three quarters unloaded In the final step, the inlet valve L remains open and ports 12 and q register with ports a f The cycle is indicate y and. m respectively so that both chambers G and H are open and the compressor-is completely unloaded. p d by the diagrams in Figurefi showing that instep I, the clearance chamber F at the crank end of, the cylinder is open to producethree quarters load. 'Then this chamber F is closed as indicatedin step II and both chambers G and H at opposite ends of the cylinder are open producing half load. In step'III. the crank end of the cylinder is wholly unloaded due to the opening of the inlet valveL and one clearance chamber G is indicated. as being open at the opposite end of the cylinder,

while in step IV. both chambers at the head endo f'the cylinder-are again open as in step ILsoth'at the compressor is wholly unloaded since .the inlet valve at the crank end re-' mains open. j' The modificat on shown in Figure 7,'the

pipe 1 leadingto *the clearance valve mechanism of chamber F is. connected to the -7a in the cylinder a, and in the first step of unloading, the port k in the piston b regisport ters with the port hso that the clearance 7 quarters. load. This clearance'--chamber F chamber, F is'first opened to produce three.

then remains open throughoutthe cycle of so that wboth clearancechambers G- and H at" 35 the head end of the cylinder are open. completely unloading this end of the cyllnder and in conjunction with the open clearance chamber F at the crank end of the cylinder, producing one quarter load. In the final step, ports p, q and 1" register respectively with ports 13, 12 and 14, the port 13'being con-' nected directly to pipe 2, and the port 14 being connected-to the. pipe 4 which leads to clearance chambers G and H at one end of the cylinder are open and the inlet valve L.-

atthe'opposite end of the cylinder is' open .to produce a no load condition.

The indicator diagrams in Figure 8 illus trate the cycle of Figure 7 showing that for "the first step, the chamber Fat the crank endof the cylinder is open forthree quarter's load and them this phamb'er'remains open through steps I, II- and III and may remain 'open in step. IV, although this is immaterial. In step II, one clearance clfamber isopen at each end of the cylinder for half load. In step III, both chambers G and H are open at.

the head end of the cylinderfor one quarter U load, and in step IV,.the two chambers G and H remain open and the inlet valve L at of the cylinder is openv for no.

the crank end load.

I'claim: I 1. In a. compressor unloader, the combination of a cylinder and piston, inlet and dis-- charge .valves, a 1 receiver, two clearance chambers and clearance valves "for one-end of the cylinder a clearance ehamben and.

valve and an inletvalve opener for the lip-- posite endof thepylinder, and pressure flu d means for manipulating said clearance ,.valves and inlet valve opener to efl'ect, steps of unloading. f

2. Ina. compressor unloader, the combination of a cylinder and pist/om'inlet and discharge valves, a receiver, a clearance chemher and clearance valve and an inlet'v'alve' opener for one end'of. tl1e cylinder, and-a5 9 the valve opener ofthe valve L so .that both plurality of clearance chambers and clearance valves for the opposite end of the chamher, and a regulator responsive to receiver pressure controlling all of said clearance valves and the inlet valve opener, whereby the compressor is unloaded in steps.

3. In a compressor unloader, the combinationof a cylinder and piston, inlet and dis: charge valves, a receiver, a plurality of clearance chambers and clearance valves for the cylinder and an inlet valve opener for one end of the cylinder, a regulator controlling the clearance valves and inlet valve opener, and connections for partially orwholly unloading one end of the cylinder by means of the clearance chambers, and for unloading the opposite end of the cylinder in steps by means of one clearance chamber and the illlet valve-opener.

In testimony whereof I have signed this specification. \1 v SNOWDEN B. REDFIELD. 

